FIGS. 1A and 1B are left (driver side) and right (passenger side) elevational views, respectively, of a conventional semi-trailer T adapted to be connected to and pulled by a conventional tractor/truck (not shown). The trailer T comprises a forward end FT and a rear end RT spaced-apart from each other on a longitudinal axis L. FIGS. 2A and 2B are plan and cross section views of the trailer T as taken along view lines A-A and B-B of FIG. 1A, respectively. Referring also to these drawings, it can be seen that the trailer T further comprises a cargo-supporting platform P including left and right laterally spaced-apart sides LP,RP. The platform P is supported by and connected to a chassis C that includes first (left) and second (right) spaced-apart beams B1,B2 that extend parallel to each other and to the longitudinal axis L from the forward end FT to the rear end RT. Each beam B1,B2 defines an I-beam profile comprising an upper flange F1 and a lower flange F2 (FIG. 2B) connected by a web BW. The beams can be steel or aluminum and are often fabricated by welding or otherwise abutting and welding together or otherwise connecting two separate T-shaped aluminum extrusions.
A kingpin K is located at the forward end FT of the trailer T, centrally located between and connected to the beams B1,B2, and is adapted to be engaged by a fifth-wheel of an associated tractor/truck for towing the trailer T. The rear end RT of the trailer includes at least one and typically at least two axle assemblies A connected to the chassis, e.g., to the lower flanges F2 of beams B1,B2. Each axle assembly A comprises at least one left and at least one right rotatable wheel and tire assemblies W for movably supporting the trailer T on a road or other surface. The trailer T further comprises a dolly assembly D, typically located axially between the kingpin K and an axial midpoint of the trailer T. The dolly assembly D includes support feet DF that are selectively lowered to support the forward end FT of the trailer T when the kingpin is not connected to an associated tractor/truck (the dolly assembly D is omitted from the background of FIG. 2B for clarity).
The platform P comprises left and right side rails RL,RR that delimit the opposite lateral sides LP,RP of the platform, respectively. These side rails RL,RR are each typically defined as one-piece or monolithic extrusions of aluminum alloy (often referred to herein simply as “aluminum”) having a profile such as that shown in FIG. 2B and that extend in one piece from the forward end FT to the rear end RT of the trailer T, and that lie in respective vertical planes that are parallel to the webs BW of beams B1,B2 and the longitudinal axis L (the profiles of the side rails RL,RR are typically mirror images of each other as shown herein). The side rails RL,RR are often arched as shown in FIGS. 1A and 1B with an apex of the arch oriented upward and located between the forward and rear ends FT,RT.
The platform P, itself, comprises left, middle and right sections PL,PM,PR that each comprise one or more wood and/or metal longitudinally extending platform members PK, each of which extends longitudinally from the forward end FT to the rear end RT of the trailer T, as one-piece or otherwise to define an upper cargo-supporting surface P1. Typically, the platform members PK comprise aluminum extrusions and/or wooden planks or the like. Regardless of the material used to define the platform members PK, it should be noted that they extend longitudinally between the forward and rear trailer ends FT,RT, but do not extend transversely between the left and right side rails RL,RR, i.e., each platform member PK fills only a fraction of the space between the left and right side rails RL,RR. In the illustrated trailer embodiment, the upper flange F1 of each beam B1,B2 also defines part of the platform P, with the upper flange F1 of the first (left) beam B1 connected to both of the left and middle platform sections PL,PM and the upper flange F1 of the second (right) beam B2 connected to both of the right and middle platform sections PR,PM.
In each of the left, middle, and right sections PL,PM,PR, the platform members PK extend in a longitudinal direction that is parallel to the axis L and beams B1,B2, but platform members PK from each section PL,PM,PR do not extend transversely from one section PL,PM,PR to another section PL,PM,PR. If the beams B1,B2 and side rails RL,RR are arched, the platform members PK are correspondingly arched. As such, to support the longitudinally extending platform members PK, the platform P of trailer T must further comprises a plurality of transversely extending cross members CM located beneath the platform members PK at axially spaced intervals along the entire length of the trailer T. The cross members CM are welded or otherwise connected to and extend between the left and right side rails RL,RR, passing through and typically welded to the beams B1,B2 (in some cases the cross members CM comprise three separate sections cross member sections located respectively beneath and supporting the left, middle and right platform sections PL,PM,PR instead of a single member that passes through the beams B1,B2). These cross members CM can have a variety of shapes, e.g., I-beam, U-shaped, C-shaped, etc. and be defined from a variety of materials such as steel or aluminum, e.g., aluminum extrusions. The use of cross members CM increases labor and material costs, and the cross-members create an uneven underside P2 to the platform P which increases wind drag and/or includes locations for dirt, ice and other debris to accumulate between the cross members.